For example, Japanese Patent Application Laid-open No. 2009-27221 (Patent Literature 1) discloses a technique of assigning phone numbers or e-mail addresses registered in a phone book or an address book to face images of persons who own the phone numbers or e-mail addresses and making it possible to easily identify a person as a communication target based on the face images to perform communication. In particular, in Patent Literature 1, from a picture image obtained by shooting a plurality of persons, face areas of the plurality of persons are extracted, and the face areas extracted can be associated with corresponding persons' phone numbers or e-mail addresses and collectively registered.
Further, for example, Japanese Patent Application Laid-open No. 2005-157679 (Patent Literature 2) discloses the following technique. A large number of information items on face images are previously learned and stored as dictionary data, picture images that are input are set as grayscale images, window images are cut off from scaling images obtained by scaling the grayscale images, the window images are compared with the information items stored as the dictionary data to determine parts close thereto. When this processing is repeatedly performed, a face image can be easily and quickly detected.